A method for separating collected blood into blood cells and plasma has been known in the art (e.g., JP Patent Publication (Kokai) No. H7-294516 A (1995)).
Known examples of separating agents used in such blood separation operations include a polymer compound for forming separate layers (a) such as a silicone oil, chlorinated polybutene, polyisobutene, an acrylic polymer, a copolymer of α-olefin having 6-20 carbon atoms and dimethyl maleate, and styrene.dimethyl maleate copolymer as a main component, mixed with a thixotropic agent (b). Such compositions have been used in practice.
Known examples of thixotropic agents include inorganic fine powders (silica, clay, and the like), and organic gelling agents such as a condensation product of sorbitol and benzaldehyde (dibenzylidene sorbitol), hydrogenated castor oil, 12-hydroxy stearic acid, a nitrohumic acid adduct of water-soluble protein, glutamic amide, dimethanol octahydronaphthalene copolymer for the control of specific gravity and viscosity.
Further, a method for accommodating a previously collected blood sample in a container together with a blood dilution buffer and assaying biological components of such blood sample in such container has been conventionally known.
Assay of the biological blood components using a minute amount of blood in a container accommodating such previously collected blood sample can be utilized for early detection of health status, diseases, and presymptomatic states.
This approach is advantageous in that the time and location at which blood is collected for blood testing can be freely determined.
In the above case, it is necessary to transfer the container containing the collected blood sample from the site of collection to the site of sample analysis. That is, it becomes necessary to accommodate and store the blood sample in a container according to the present invention. In order to obtain accurate analytical results for a collected blood sample, it is essential to minimize changes in the state of the blood sample by keeping it in a container together with a dilution buffer during storage.
One known method for storing a blood sample is a method comprising diluting blood with a blood dilution buffer containing an internal standard, separating the diluted blood cell component from the diluted plasma component via a filter (i.e., filtration means), and storing the resultant in a container (see, e.g., JP Patent Publication (Kokai) No. 2001-255323 A).